1. Field of Invention
The present invention relates to a voltage control oscillator. More particularly, the present invention relates to a voltage control oscillator that is adjustable.
2. Description of Related Art
Oscillators are critical elements in circuit design nowadays, including both analog circuits and digital circuits. A voltage control oscillator (VCO) is a kind of oscillators that generates oscillating signals according to a reference voltage input to the voltage control oscillator. In other words, different reference voltage input determines different oscillating frequencies in voltage control oscillators.
Even the voltage control oscillator has been developed for a long time, new designs and challenges do not stop because quality requirements of electronic equipments become higher and higher.
Output frequency bias or phase noise of voltage control oscillators often occur due to material limitations or control difficulty of manufacturing process in mass production. Things become more difficult because such problem usually occur after assembly process of voltage control oscillators has completed. Therefore, it is a great challenge to efficiently control yield rate of voltage control oscillators.
Another common problem is that size of circuit boards are required to be more compact so that electronic devices can be made more and more smaller. It is also a great challenge to utilize every space of circuit boards to efficiently utilize every possible space.
In addition, more and more high frequency products, e.g. wireless phones or wireless networks, are developed for the market. While SMT (Surface Mounting Technology) is so popular, discontinuous effect response to high frequency in electrodes of such electronic devices using SMT to mount them on printed circuit boards often makes high frequency products instable. Therefore, it is more and more important to find a efficient method to manufacture high quality voltage control oscillators.